Low melting crushable tungsten alloy



2,777,765 LOW MELTING CRUSHABLE TUNGSTEN ALLOY John L. Benham, Lewiston, N. Y., assignor to Union Carhide and Carbon Corporation, a corporation or New York No Drawing. Application October 11, 1955, Serial No. 539,925

7 Claims. (Cl. 75-122) 3370 C., ingredient in a molten metal bath. This objection has been overcome to some degree by combining the tungsten with a metal of lower melting point, such as iron, to form a ferrotungsten alloy, which is more easily fusible than tungsten alone, and which therefore may be more readily converted into a molten state. A ferroalloy containing 30% tungsten is admirably suited for such purposes, since it has a melting point in the vicinity of only 1550 C. Theoretically ferrotungsten alloys having 30% tungsten represent an excellent starting material for producing certain engineering alloys. However, 30% ferrotungsteu alloy is very tough, and is virtually incapable of being crushed by normal means. In granular form, this ferrotungsten is admirably suited to be melted and formed into ingots, in accordance with the method described in U. S. Patents 2,191,479, 2,191,480 and 2,191,481. it practically feasibl tu granulated condition for alloying or other metallurgical purposes would be simplified.

Percent W 30.00. Cr 29.00. C 1.00 max. Fe and incidental impurities Balance.

commercially and e to crush these ngsten alloys, the problem of using them in crushed or 2,777,765 Patented Jan. 15, 1957 Crushable tungsten alloys with the foregoing composition ranges generally have a melting point approximately between 1270 C. and 1325 C.

An obvious advantage of the be produced in a conventional induction furnace by adding ferrotungsten alloy to a bath of substantially pure iron containing additions of either 10 being is slightly above the meltand poured at that temperature.

still more fully the nature or the approximately 1675 C., which ing point of the alloy,

In order to indicate sten alloys of the invention.

percent percent Each of the above alloys was comminuted in a convenal crusher to particle sizes capable of passing through Alloy I was crushed with extreme difliculty, the crusher apparatus jamming several times during the course of operations. Only about 8% of alloy I was sufficiently reduced in size to pass through a screen having 'WO inch openings, the smallest particle size produced being of the order of 1 /2 inches. The remaining portion of alloy 1 ranged in particle dimensions up to about 4 inches.

In contrast, 20 pounds of the alloy ll of the invention were crushed with ease to a maximum particle size of two inches, and further reduced to a maximum particle size of "fez inch (8 mesh size) in conventional crusher equipment. This crushed alloy was then milled for one hour with comparative ease to produce the following results:

Screen Size Alloy II I Alloy ll Tyler Series Before After M ill- Milling ing 1 Hr. Mesh Retained on 8 0. 5 Nil Do 20 54.0 1.0 Do- 48 26. 0 6. 5 Do 100 8. 0 22. 5 D0 200 5. 0 20. 5 Passing Through 200 6. 0 Do 325 12. 0 D0 325 37. 5

5 proportions are entirely suitable as engineering alloys.

V taining 26% to 33% -What is claimed is:

- 1. An alloy containing 26% to 33%- 32% chromium, and the remainder iron and incidental impurities.

2. A mass of finely divided particles composed of the the alloy defined by claim 1.

3. A low melting, crushable,'ferrotungsten alloy con- 7 tungsten, 25% to 32% chromium, andthe remainder iron and incidental impurities.

4. An alloy containing 26% to 33% tungsten, 25 to 32% chromium, and the remainder iron and incidental impurities, said alloy being further characterized in that its melting point lies approximately between 1270 C. and 1325 .C. and has a greater degree -of crushability than binary ferrotungsten alloys containing approximately the same amount of tungsten.

.to 33% tungsten, 25% to and the remainder 5. An alloy containing 26% 32% chromium, up to 1.0% carbon, iron and incidental impurities.

tungsten, 25% to a 6. A ferrotungsten alloy required to fuse at a temperature approximately between 1270 C. and 1325 C., and having a low resistance to reduction in particle size, said alloy containing 26% to 33% tungsten; 25 to 32% chromium, and-the remainder iron and incidental impurities.

7. A ferrotungsten chromium alloy adapted to be pulverized to particles smallerthan 20 mesh size, and having a melting point between 1270 C. and 1325 C., said alloy containing approximately 30% tungsten, approximately 29% chromium, up to 1.070% carbon, and the remainder iron and incidental impurities.

References Cited in the tile of this patent UNITED STATES PATENTS 1,357,550 Fahrenwald Nov. 2, 1920 1,471,326 Copland Oct. 23, 1923 1,593,924 Wirth July 27., 192.6 

1. AN ALLOY CONTAINING 26% TO 33% TUNGSTEN, 25% TO 32% CHROMIUM, AND THE REMAINDER IRON AND INCIDENTAL IMPURITIES. 